The OP here seems to think that BG3 has to adhere to a very rigid interpretation of the hard rules presented in the 5E core books in order to feel like D&D.
I disagree with this, on the grounds that D&D itself is not really about adhering to the hard rules presented in the core books.
The rules in the core books should be a starting place for a DM to learn how to adjudicate the things that happen in the game for which there are no rules. For example, if a player somehow starts a fire in a cave where bandits are hiding, the DM should not say:
“Well your fire doesn’t do any damage because sustained AOE damage normally requires concentration.”
Instead, the DM should just pick some kind of reasonable damage and have the fire does, and have it damage the bandits every round. This is basically equivalent to a surface effect.
Same difference with if a player tries to drop a Huge chandelier on an enemy. The DM should not say:
“Well at your level you can only do a max of 1d10+4 per round, so the chandelier only does 5 damage.”
That’s lame. The chandelier should do whatever damage seems reasonable for 300 pound hunk of metal and glass falling on someone from 50 feet high would do.
This kind of thing, this dynamic gameplay that is not necessarily laid out in the rulebooks is very common in D&D.
But most D&D video games don’t allow for any of this, or it’s extremely situational.
But with BG3, they actually put mechanics like, surfaces, environmental effects and height advantage into the game that let you do a lot more of this unconventional stuff that normally can only happen in pen and paper D&D.
I feel like taking this out in order to present a more bog standard D&D video game would be a terrible mistake.
There's a big difference between "The spirit of the game" and the "rules as written".
I agree, the game doesn't have to doggedly replicate the rules of tabletop to be a great game.
There are going to be compromises that have to be made in service of making a fun video game.
I think there's room for improvement for sure, but I enjoy seeing a unique take on the system.
I love environmental effects and interaction. It rewards so much more than just rolling against stat blocks.